Product Description
There's a conversation that happens on almost every drilling project, usually around day three, when something starts leaking. Someone walks over, looks at the connection, and says: "I think it's the wrong thread."
And they're often right.
The BDL122 is a 1/2-inch female thread (interno) air coupling — meaning it has internal threads that screw onto a male-threaded fitting on your equipment. Getting the thread right isn't just about fit. It's about pressure integrity, safety, and not having your crew standing around while someone drives to the nearest hardware store (which is 90 minutes away, and doesn't have the right part anyway).
Understanding Thread Compatibility
This is worth spending a moment on because it's the single most common source of coupling problems we hear about from customers.
The BDL122 uses standard 1/2-inch female threads (G1/2 or BSPP — British Standard Pipe Parallel). This is the most widely used thread standard for pneumatic equipment in mining and construction. If your jack hammer or air compressor has a 1/2-inch male thread outlet, the BDL122 will thread onto it directly.
Here's where people get caught:
BSPP (G threads) vs NPT (American National Pipe Taper): These are NOT interchangeable. BSPP threads are parallel; NPT threads are tapered. They might start to thread together, but they won't seal properly, and the connection will leak under pressure. The BDL122 uses BSPP (G1/2).
Thread size isn't hose size. A 1/2-inch thread doesn't mean 1/2-inch hose. Your thread size is determined by your equipment's port. Your hose size is determined by your air delivery requirements. They're independent.
If you're unsure about your thread type, check your equipment manual or measure the outer diameter of the male threads on your drill's air inlet. A G1/2 thread has an outer diameter of approximately 20.95 mm. NPT 1/2" is slightly different at approximately 21.22 mm — close enough to confuse, different enough to leak.
Where the BDL122 Fits in Your Air System
The BDL122 isn't a hose clamp. It doesn't go around the hose. It goes on the equipment side of your connection.
A typical setup for a hand-held rock drill looks like this:
Air Compressor → (hose with abrazadera SL34 or SL40) → Air Line → BDL122 (female thread, screws onto drill inlet) → Jack Hammer
The BDL122 adapts between the air delivery hose and the drill's threaded inlet port. On many smaller drills — the Y24, Y26, B47 pneumatic breaker, G16 air pick — the air inlet is a 1/2-inch male thread, which makes the BDL122 the correct matching coupling.
Construction and Sealing
The BDL122 is manufactured from brass, chosen for its corrosion resistance in the damp, pressurized-air environment that pneumatic equipment operates in.
For sealing, apply 2–3 wraps of PTFE (Teflon) tape to the male threads before screwing on the coupling. This fills the microscopic gaps between the threads and creates the airtight seal that keeps your system at working pressure. Tighten by hand until firm, then give approximately 1/4 to 1/2 turn with a wrench. For an M10-sized thread (which is roughly equivalent), the recommended torque is 15–20 N·m — enough to seal, not enough to strip.
Avoid these common mistakes:
Don't use pipe joint compound (liquid sealant) and Teflon tape together. Pick one.
Don't over-tighten. You'll crack the brass or deform the threads.
Don't force a cross-threaded connection. If it doesn't thread smoothly for the first two turns, back off and realign.
Technical Specifications
| Specification | Detail |
|---|---|
| Product Code | BDL122 |
| Type | Interno (female/internal thread coupling) |
| Thread Size | 1/2 inch (G1/2 / BSPP) |
| Thread Gender | Female (internal) |
| Working Pressure | 0.4–0.63 MPa |
| Material | Brass |
| Sealing Method | PTFE tape (2–3 wraps) |
| Compatible Equipment | Y24, Y26, B47, G16, G15, G12, C6 pneumatic tools |
| Unit Price (EXW) | ~$0.85 USD |
Frequently Asked Questions
Q: How do I tell if I need female (interno) or male (externa) thread? Look at the port on your equipment. If the threads are on the outside (a stud or nipple sticking out), you need a female coupling (interno) — the BDL122. If the threads are on the inside (a socket or recessed hole), you need a male coupling (externa) — see our BDL112.
Q: Will this work with NPT threads? No. The BDL122 uses BSPP (G1/2) threads, which are not compatible with NPT 1/2". Using incorrect threads will result in leaks and potentially unsafe connections. If your equipment uses NPT, look for an NPT-specific coupling.
Q: How many times can I remove and reinstall this coupling? A quality brass coupling like the BDL122 can handle 10–20 installation cycles before the threads show wear. Inspect the threads each time you remove it — if you see galling, flattening of the thread peaks, or difficulty threading by hand, it's time to replace.
Q: Do I need to use sealant on every installation? Yes. Even if the coupling sealed perfectly the last time, always apply fresh PTFE tape when reinstalling. The old tape will have compressed and may not reseal properly. It costs almost nothing and takes seconds.
